The present invention relates, in general, to electrical connectors and, in particular, to a new and useful electrical connector block for making connections to a flat ribbon cable having a plurality of conductors lying side by side in an insulating ribbon.
The proper grounding of electrical equipment is important since transients may be generated internally or externally of the equipment which must find a pathway to ground or else damage may occur to the equipment or injury may occur to persons handling the equipment.
Transient protectors absorb this energy and minimize damage or prevent excessive voltage from leaving the equipment. Typically the transient protectors are soldered onto a circuit board or to a connector. High density boards have little room for such transient protectors, however. Standard insulation displacement connectors do not have exposed metal where the transient protectors can be added.
A particular danger may exist in CRT's (cathode ray tubes) where high voltage in the CRT's could propagate outside the enclosure of the devices via signal lines connected to the devices. Such propagation can cause fire, shock and/or equipment damage. Another concern is that the high voltage in the signal wires can arc over to other circuits or bare metal. If these wires are connected to equipment in a hazardous location, such as in the proximity of flammable or explosive material, this arc can cause ignition of this material.
It is desirable that any voltage on any signal leading out of a CRT be less than 250 volts a.c. with respect to ground (earth). The anode voltage in a CRT could be 14,000 to 35,000 volts. The capacitance of the anode could be 500 to 2,500 pFd.
Transient protectors for lines leaving a CRT would thus be desirable, particularly in view of the small amount of space which is generally available on circuit boards of such devices.
Electrical connector blocks having insulation-piercing bifurcated contacts or tines for the formation of electrical connections have been described in U.S. Pat. Nos. 3,012,219 and 3,820,058. These connector blocks include one or more rows of insulation-piercing contacts for piercing the insulation of a multi-conductor ribbon cable or other insulated conductors. Also, a number of connector blocks are known in the prior art for common or ground termination of alternate drain conductors or a ground plane in a multi-conductor flat ribbon cable. Such connector blocks are disclosed in U.S. Pat. Nos. 3,634,806, 3,731,251, 3,864,011 and 3,912,354.
The prior art does not teach the placement of signal conducting resistors or surge suppression devices in shunt or parallel with two or more conductors in a ribbon cable.